This invention relates to the act of reproducing multiple copies from a master motion picture film and is particularly concerned with arrangements whereby the quantity of light permitted to be passed to the film can be automatically and rapidly varied to desired and predetermined extent in programmed sequence.
Multiple copies of the final edited film on which the scenes photographed from life or from cartoon drawings appear, are usually obtained by the industry by contact printing. Such reproduction is accomplished by passing a beam of light through the master film and onto an opposed sensitized blank film running in registry therewith. During such printing it has been the practice in the art to provide the printer with instructions on the quantity or intensity of light to be utilized with each change of scene on the master films, so that variations in density in the exposure being copied can be smoothed out to obtain a well-balanced reproduction for projection purposes. Variations in the quantity or intensity of light passed through is particularly important in printing of color film. In certain industrial applications, an automatic color analyzer programs color adjustments to be made by the printer. These programmed adjustments may be recorded on tape fed to control the color printing, to make density changes as well as color corrections by changing the mix of color densities. In each film copying machine for color printing, the light is divided into its three primary colors: blue, green and red. The intensity of each of these colors, which by their combination in regulated proportions determined the color reproduced, can be controlled to practical extent by increasing or diminishing respectively the light transmitted in the reproduction of each of these colors. The quantity of light contacting the film is readily controlled by regulating the size of the orifice or shutter opening through which the light from a given source is passed. The skilled editor in viewing the original film scene by scene, determines for each scene the best lighting conditions for printing the respective scenes. These conditions are tabulated in various manners known in the industry and the master film is marked with certain identification means at the start of each scene to provide a cue for the printer to apply the prescribed lighting as identified by the editor's tabulation of lighting conditions desired. The prescribed changes in lighting conditions from scene to scene must be made while the running film traverses the light beam which necessitates a degree of rapidity, particularly in short scenes, such that very few frames are permitted to pass before the change is accomplished. Typically with the film moving at the rate of approximately 120 frames per second, the change in light conditions must be achieved in less than 5 milliseconds which corresponds approximately to the time that one-half of a frame passes the beam of light.
Automatic devices for control of certain types of shutter operating mechanisms have been proposed in the past, which rely for the most part on the use of complex and expensive systems of electrical switches and relays. Among the objectives of the present invention is to provide a mechanically operating simple and relatively inexpensive mechanism for effecting rapid and automatic changes in shutter openings on prescribed schedule.